1. Field of the Invention
The invention relates to a method and apparatus for coating caplets with gelatin.
2. Background of Related Art
The concept of coating tablets or caplets with gelatin is known in the prior art. Pills or tablets having gelatin coatings are described in the patent literature, for example see U.S. Pat. Nos. 2,410,110 or 3,275,519.
There appear to be two primary methods of applying a gelatin coating to a pill. The first method is to hold the pill or tablet during the dipping process. The second method is to spray a coating over the pill as it tumbles. U.S. Pat. No. 599,865 issued Mar. 1, 1898 discloses an early system in which a pill is held at one end by bees wax in a holder while its other end is dipped. The pills are then transferred in such a way as to hold the previously dipped end while the non-dipped end is then coated with gelatin.
A machine for dipping capsules while holding the same by means of a vacuum above a gelatin filled pan is described in U.S. Pat. No. 540,538 issued on June 4, 1895 to A. Colton.
Other methods for providing a coat to a pill are also described in the following U.S. Pat. Nos.: 2,853,421; 3,185,626; 3,431,338; 3,607,364; 4,670,287; 4,705,695 and Australian Pat. No. 100,146 accepted June 19, 1937.
Patents which disclose the technique of coating a tablet with gelatin or similar substance by either spray-coating or immersing the tablet in a bath are disclosed by the following references: U.S. Pat. Nos. 1,416,796; 3,141,792; 3,573,966; 3,991,225; 4,118,522; 4,129,666; 4,581,242 and 4,725,446.
U.S. Pat. No. 2,373,721 is of interest in that it discloses an apparatus for coating small objects such as pills, tablets and the like with gelatin. The tablets are held in place by suction while they are coated. Other mechanisms of possible relevance include the disclosures in the following U.S. Pat. Nos.: 229,785; 542,611; 2,596,176; 2,727,473; 2,997,018 and 4,407,844. Other U.S. Patents of possible interest include U.S. Pat. Nos. 724,436; 3,045,641; 3,896,762 and 4,238,510.
A recent interest has been shown in the concept of coating a caplet with gelatin. Such products are known as "gelcaps". A method and apparatus presently used to coat caplets is described in European Pat. Application No. 0 279 682 published on Aug. 24, 1988. According to that document, a caplet is held in a collet which in turn is held in an elongated bar. The bar is similar to a pin bar on a typical Colton Model 950 gelatin capsule making machine. The caplet is dipped in the dipping pan and then dried. It is subsequently brought into alignment with another elongated bar and the caplet is transferred from one bar to the other by means of a pin. The other side of the caplet is then dipped and forced out by the incoming caplet.
The foregoing mechanism is relatively inefficient because it requires the modification of an existing Model 950 Colton gelatin capsule machine or its equivalent. The machine can only operate on one row of caplets at a time. However, the machine is able to take advantage of some of the features that preexisted on the original Colton machine.
It has been found, however, that the speed of the converted Colton machine is relatively slow and the process requires many steps, some of which are left over from the original gelatin capsule making process.
It is interesting to note that the late Arthur Colton, the founder of the company that makes the Model 950 Colton gelatin capsule machine, had himself invented a machine for dipping tablets and gelatin. The invention is described in U.S. Pat. No. 540,538 entitled MACHINE FOR DIPPING PILLS and issued on June 4, 1895. The machine described in U.S. Pat. No. 540,538 holds pills in a tray by suction while the pills are dipped in a bath of liquid gelatin.
The general concept of holding a tablet or caplet in a split collet and then ejecting same with a rod is a technique that already exists on non-converted Model 950 Colton gelatin capsule machines. The same technology is also described in the prior art patent literature. For example, U.S. Pat. No. 2,671,245 entitled CAPSULE MACHINE and issued to A. W. Kath on Mar. 9, 1954 and assigned to Eli Lilly & Co., Indianapolis, Ind. shows the general state of the art. Gelatin caps or bodies are formed by dipping rods into a bath of liquid gelatin and permitting them to dry. After the gelatin caps or bodies have dried, they are stripped off into holding collets. One set of collets holds the capsule bodies and another parallel set of collets holds the capsule caps. Rods passing through the center of the collets push the gelatin caps and bodies towards each other in a mating plate where they form an empty gelatin capsule.
A similar machine is described in U.S. Pat. No. 1,787,777 issued to A. Colton and entitled Capsule Machine published on June 6, 1931. The patent is noteworthy again for the showing of the holding of a capsule-like body in a split collect chuck prior to assembly as a complete gelatin capsule. Another more advanced version of the same type of invention is described in U.S. Pat. No. 2,373,721 entitled Apparatus for Coating.
Similarly, note U.S. Pat. No. 961,936 issued on June 21, 1910 to A. Colton and B. W. Scott and entitled Machine for Making Capsules. This patent also shows the early state of the art with reference to the concept of holding a capsule-like body in a chuck having the characteristics of a collet.
Lastly, U.S. Pat. No. 2,727,473 entitled Coating Mechanism issued to J. E. Wolff et al. on Dec. 20, 1955 describes an invention in which tablets are coated on both top and bottom while held in a receiver and manipulated up and down.
The inventors have discovered that they can substantially improve upon the speed, efficiency and quality of the product in the manner set forth below.